REST: A Pragmatic Introduction to the Web's Architecture

Recorded at:

Summary
In this presentation, recorded at QCon London, Stefan Tilkov introduces the key principles of REST, explaining the differences to other distributed systems architectures and highlighting its benefits. Topics covered include mapping business logic to resource interactions, hypermedia, and documentation.

Bio

Stefan Tilkov is co-founder and principal consultant of innoQ, lead SOA editor at InfoQ, and a long time advocate of using RESTful HTTP to reach the high-level goals of SOA.

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It would be interesting to get Stefan's opinion of Ross Altman's latest presentation. Ross is one of Sun's CTOs (for Business Integration) and he explains:

Assumption: RESTful Web services should be used instead of WS-* Web services

A case can be made for the use of RESTful services for Opportunistic applications. However, for Systematic applications, the Qualities of Service that are required would have to be built on an ad hoc basis.

As a result, the cost of RESTful services would go up and interoperability would go downIf the counterparties building a RESTful interaction have to “reinvent the wheel” of runtime governance standards, the costs and complexity of RESTful Web services would increase dramatically, undermining the attractiveness of the REST model

Since the runtime management capabilities for each RESTful Systematic application would be developed in a non-standard way, interoperability between RESTful implementations would drop drastically

As you're asking for my opinion: No, I don't believe that WS-* will have to be re-invented for RESTful HTTP. For example, I believe that there are many, many more opportunities for runtime governance of RESTful HTTP services already, as the infrastructure has much more visibility into the messages flowing through it.

Could you explain how these pieces work in REST since there are no contracts, no boundaries, no policies, no agreed upon versioning capability, URIs are bolted on resource access operations (making it hard to deal with Change) and finally, how do you go about conducting a root cause analysis across a domain that has no autonomous boundaries (i.e. where the only explicit boundary is the network authority that owns a particular URI).

When you build a Web App, you can monitor if it's up or down, and how it is behaving. When you cover a network authority with a series of "resources" where do you start when an event/incident/problem occurs? You go straight back to the design doc? you have no impact analysis capabilities?

1) Are you suggesting there are widespread runtime governance standards for WS-*? Like what? UDDI? Currently, every governance product uses its own proprietary approach.

2) You are free to use XML Schema, as much as you want to, when using RESTful. If you want to base part of your governance on the evolution of schemas, nothing stops you.

3) There is no versioning support in WS-* that I'm aware of. The stuff I've read about it (including yours) talks about options for XML Schema versioning, which IMO a) still sucks b) is available for REST/HTTP if you disagree

4) While I've seen tons of articles and presentations discussing the use of policies for governance, I've never seen it applied in practice.

5) The impact analysis support I've seen in governance product requires additional metadata that has to be explicitly added, such as usage relationships between consumers and providers. This seems to be entirely orthogonal to the REST vs. WS-* discussion in my view.

6) I fail to see how URIs make it hard to deal with change - in fact I disagree strongly. They offer a workable means to support old, new and unknown clients that I've not seen in the WS-* world.

As methods like POST, GET has data size constrain, number of byte you can send. How can we send large data?

Or better I want to know,if we building system with lot and lot of complex data. Is REST is good choice ? Possibly we can do it in REST.Amount of effort we put for development and maintaining the application will be huge as compare to using WS based on SOAP.